Fixup xcode project dependencies
Continue renaming types PLobject -> pl_object_t
Hook up libcelmek with openorbit.

This also adds a rudimentary n-body simulation code which is needed for
gravity computations.
Fix inconsistency with naming in solsystem.hrml and the naming in libcelmek
Fix memory leak
Fix slider bounds in io code
Should use format when passing buffers to openal
Kill unused file
Name in solsystem.hrml does not match libcelmek names
Add menu to set camera target
Fix naming of orbits, in the menu they where indistinguishable from
the planets themselves.
Add texture of Uranus
Lwcoord uses long for integer part

Changes occured in vmath 44260fbdcd18da0973d3f9128ceb981d910e1ca1. This
commit ensures compatibility with the vmath changes.
Kill dead code
Add dummy argument to menu test function
Use rotation matrix for drawing ellipses.

Instead of creating an ellipse in the space it is located in, we now use the
rotation matrix to position it correctly. This means that we can more easily
accommodate for osculating elements.
Fix light computation

We are only interested in the camera orientation here as the distance is
already accounted for in the dist vector.
Handle celestial objects in modelview-sync
Terminator computation requires the use of negative ndotl
Add camera move forward and backward controls